Electric soldering iron



Mayzl, l929 E. A. LocKwoon 1,713,845

ELECTRIC SOLDERING IRON Filed Nov. 22, 1926 7x/Ma aa Afa/ami' ff wwwAuw. 1mm #64M Patented May 21, 1929.

UNITED STATES PATENT omnes.

EBWIN A. LOCK'WOOD, 0F ROYAL OAX, MICHIGAN, ASSIGNOR TO AMERICANELECTRI- CAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORATION 0FMICHIGAN.

ELECTRIC SOLDERIN G IItON.

Application `led November 22, 1926. Serial No. 150,018.

The invention relates to electrically heated instruments and moreparticularly to electric soldering irons of the type in which a centralmetallic core member is heated by an electrical resistor surrounding thesame in close proximity thereto.

With instruments of this type as heretofore constructed it has been theusual practice to form the electrical resistor by winding a conductorcircumferentially of the core member and spaced therefrom only by a thmlayer of insulation, such as mica. When such a construction is subjectedto alternate heating and cooling, it has been found that the metallicconductor gradually contracts in length and this contraction increasesthe tension on the windings so that they are drawn more tightly aroundthe rigid core member. Since this core member is unyielding, the tensionsometimes increases to such an extent that a failure occurs, thusdestroying the resistor and requiring a replacement unit.

The primary object of this invention is to provide an improved resistorconstructlon so arranged as to permit contraction of the windings undervarious temperature conditions wit-hout placing any material additionaltension on the conductor, thus avoiding ally danger of breakage fromthis cause. This object has been attained by providing the novelconstruction hereinafter more fully described, which consistsessentially in arranging the windings to extend longitudinally of thecore and to be spaced circumferentially thereof.

The conductor is preferably wound upon a tubular insulating member,which, while normally holding the windings in fixed relation, isneverthelesssuiliciently yieldable to permit lengthwise contraction ofthe conductors without subjecting' them to any increased tension.

In the drawings:

Figure 1 is a longitudinal section the soldering iron;

Figure 2 is a perspective view showing the method of assembling theresistor on the core;

Figure 3 is a view of the resistor as wound prior to being formed into atube;

Figure 4 illustrates the resistor'after being formed into a tube.

In the preferred embodiment of my invention as illustrated in thedrawings, A represents the hollow cylindrical metallic core throughpreferably formed of a material resistant to I' high temperatures. B isthe metallic tip inshank G. H is the outer shell sleeved'on the` forwardportion of the core and retained in position by the lock nut H.

The resistor D is preferably formed as illustrated in Figure 3 bywinding a resistance element on a flat rectangular sheet of insulatingmaterial, such as mica. This fiat sheet I is provided with notches J onits opposite edges which receive the windings K. The resistance elementis preferably in the form of a flat ribbon L and this is wound aroundthe flat sheet l forming a continuous resistance unit. After theresistance element has been wound onv the flat sheet, the latter is bentinto tubular form with the windings extending longitudinally thereof.The opposite edges M and M gether, forming a split tube which is placedaround the spool portion of the core A. For insulating the resistor fromthe core it is preferable to insert a layer of mica N between the coreand the tubular resistor` and a similar layer of mica O is wrappedaround the outside of the resistor. Surrounding the insulation O ametallic sheet P is placed and the whole structure is retained inassembled position by a binding of wire, as indicated at Q, theconvolutions extending circumferentially.

lVith the construction described it will be apparent that anycontraction of the resistor windings due to alternate heating andcooling of the instrument will tend to shorten the windings in adirection longitudinally of the core and this is permitted due to theyieldable nature of the mica tube on which the resistor is wound. Thiscontraction, howof the sheet are brought towindings on the mica sheet Iare of slightly lshorter lengths for one-half of the circumference ofthe tube than for the other half, leava semi-circular portion R betweenthe ends of the windings and the edge of the tube. The terminal S istransversely bent at S and arranged circumferentially of the tube 1n theportion R and again transversely bent at S2 to extend outwardly from thetube. The other terminal T is directly extended outward from the tube atthe edge M, the arrangement being such that the two terminals leave thetube at diametrically opposite points. The terminals at these points areencased, preferably in an armor U, andare threaded through inclinedpassageways V in an insulator block V. The terminal construction at thispoint is similar to that described in Patent No. 1,425,- 983.

parent that I have provided 'a'resistor construction which can beassembled on a central y up by the contraction of the metal intheconductors after repeated use.

What I claim as my invention is: 1. A resistor unit for electricallyheated instruments having a cylindrical core, said unit i including atubular resistance element surroundlng said core and formed of a mlcasheet 35' having a conductor wound around the same with the windingsextending longitudinally and spaced circumferentially thereof, and abinding member surrounding said tubular resistance unit and insulatedtherefrom.

2. A resistor unit for electrically heated instruments having acylindrical core, said resistor unit comprising a thin sheet ofinsulating material wrapped around said core to surround the same, aconductor Wound around said sheet, the windings extending longitudinallyof said core and being spaced circumferentially thereof, insulatingmaterial on the inner and outer sides of said resistor, a metallic sheetwrapped around said resistor unit, and a binding element surroundingsaid sheet and wound circumferentially thereof.

3. A resistor unit for electrically heated instruments having acylindrical core, said unit including a thin-walled tube ofy insulatingFrom the above description 1t will be ap-l material, a conductor woundon said tube with windings extending longitudinally and spacedcircumferentially, the windings of one end of said tube extendingfurther longitudinally for one-half of the circumference than the otherhalf, one terminal from said windings being extended circumferentiallyof said tube to a point diametrically opposite the other terminal, and abushing carried by said core at the terminal end of said windings andprovided with inclined' passageways for said terminals.

4. A resistor unit for electrically heated instruments having acylindrical metallic core, said unit comprising a tubular insulatorsurrrounding said core, a resistance element wound on said insulatorwith the windings extending longitudinally and spaced circumferentiallythereof, the windings being return bent over the edges of said tube andthe return-bent portions on one half the circumference projectingfurther longitudinally than on the other half, one of theterminals o fsaid windings extending circumferentially of said tubular insulatoradjacent the return-bent portions of shorter length, said terminalleaving said tubular insulator at a point diametrically opposite theother terminal.

5. A resistor unit comprising a sheet of insulating material formed intoa tube, a flat conductor ribbon wound on saidy sheet to extendlongitudinally thereof,'the windings be'- xing spaced circumferentiallyof the tube and extending for substantially the entire peripherythereof, the opposite ends of said windings terminating at adjacentpoints and one of said ends beingcarried circumferentially of said tubeto a point diametrically opposite the other.

'6. A resistor unit for electrically heated instruments having a core,said unitincluding an insulator surrounding said core, a conductor woundon the insulator with the windings extending longitudinally thereof, thesaid windings varying in length adjacent one end of said insulator forthe purpose set forth.

7. A resistor unit for an electrically heated instrument having a core,said unit including a substantially cylindrical insulator surroundingsaid core, and a resistor wound on said insulator with the windingsextending longitudinally on opposite sides thereof.

In testimony whereof I aiix my signature.

ERWIN A. LOCKWOOD.

